In 2009, an hour and a half lecture about sugar and obesity that I gave to the public was posted to YouTube. Given its scientific content, I wasn’t even sure if my family members would watch it. Three million views later, the video is still going strong, and my theories about sugar’s toxic effects on the body are gaining traction. I still believe that one particular form of sugar—fructose—is toxic in high dose. Yet there is still a lot of confusion about this dietary bogeyman. Here are five myths about sugar and some important distinctions about how our body processes its different forms.

Myth 1. A carbohydrate is a carbohydrate; they all have the same calories.

Half true. There are three molecules that make up all the various kinds of carbohydrate: glucose, galactose, and fructose. All three molecules have the same caloric density—4.1 kcal/gm — which is why people erroneously conclude that “a calorie is a calorie.” Glucose is what’s found in starch; it’s the energy of life; all cells in all organisms on the planet burn glucose to make energy. Galactose (the molecule exclusively found in milk sugar) is rapidly converted in the liver to glucose. Fructose (the molecule that makes sugar sweet) is also metabolized in the liver, but any excess is converted into liver fat. Chronic and excess alcohol or fructose exposure both cause fatty liver disease, which drives the pathologic process of insulin resistance, and causes the same chronic diseases — obesity, heart disease, and diabetes.

Myth 2. Fructose is turned into glucose in the body.

Maybe. If you’re energy depleted (i.e. an elite athlete), fructose can be converted to glycogen (liver starch) as a storehouse for ready energy, which can then be fished out of your liver if your body needs glucose in the future (for more exercise or if you’re starving). But most of us aren’t energy depleted, so fructose gets turned into liver fat, driving insulin resistance. This is one reason why exercise can be an antidote to excess fructose consumption.

Myth 3. People can limit their sugar consumption without any difficulty.

In fact, sugar is weakly addictive. In animal studies, fructose causes the four criteria of addiction: bingeing, withdrawal, craving, and sensitization to other addictive substances (meaning after chronic exposure to sugar, it’s easier to get hooked on another drug). In humans, fructose lights up the reward center in your brain called the nucleus accumbens on MRI; but after repeated exposure, the reward center lights up less and less, so you need more and more to achieve the same effect. Fructose has effects on the reward center similar to alcohol; and just like alcohol, can lead to a “vicious cycle” of consumption and disease.

Myth 4. High fructose corn syrup is worse than table sugar.

Studies comparing HFCS and table sugar (sucrose) head-to-head show that they are similar in terms of their metabolic effects; both are equally bad for you. HFCS is 55% fructose, sucrose is 50% fructose. However, a recent study suggests that some commercial sugar-sweetened beverages might have as much as 65% fructose, which could potentially make them worse. This has yet to be shown in large studies.

Myth 5. Fructose is natural — it’s found in fruit — so it couldn’t possibly be poisonous.

Just because a chemical is natural and safe in small quantities doesn’t mean it isn’t dangerous in large quantities; e.g. Vitamin D, iron, fluoride. Yet each of these substances are on the FDA’s GRAS (Generally Regarded as Safe) list. But they don’t have abuse potential. Fructose does. A little is OK, a lot is not. And naturally occurring fructose in fruit comes with a boatload of fiber, which limits its absorption. Refined sugar has no fiber. You absorb it all immediately — that’s how the damage is done. Of course, soft drinks are the quickest way to overload your liver; but soft drinks account for only one-third of all sugar consumed. The American Heart Association has recommended cutting our added sugar consumption back by more than two-thirds; from an average of 22 tsp/day down to 6 for women and 9 for men.

As with everything, the devil is in the details. The one thing we can agree on is that our sugar consumption has skyrocketed, from 4 teaspoons a day in 1990 to 22 teaspoons today. It needs to go back to being a once-a-week treat—something for special occasions—instead of a once-a-meal diet staple.

Dr. Robert Lustig is a professor of Pediatrics at the UCSF Benioff Children's Hospital and the author of Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity and Disease. The views expressed are solely his own.

Dr. Lustig's book is Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity and Disease.

Humans evolved from fruit eating apes. Fructose has been a major component of our ancestors diets for around 130 million years. The idea that fructose is a deadly poison is utterly ludicrous. Our nearest relative the chimpanzee gets about 90% of it's calories from carbohydrates from fruit and a trivial 3% from fat.

Fruitarians are usually in far more danger of becoming underweight than obese.

Robert H Lustig thory that honey is as bad as sugar is wrong! Yes. I agree about white sugar. 100% But not about honey. Here are some facts: Beekepeers long livers:Nicholas Vitvitskiy (1764 - 1853) 89 years

Charles Butler (1560–1647) 87 years

Ian Dzerzhon (1811 - 1906 ) 95 years

There is a new article: The history of life: how Ukrainian beekeeper lived to 101 years

Well, our ancestors ate honey. Even the Bible (as an example: “Isaiah 7:15 - Butter and honey shall he eat, that he may know to refuse the evil, and choose the good.”) and Coran say that it's good for health. After all it’s made by nature from flowers or from fruit or berries. Robert H. Lustig in one of his intervievs says that he THINKS that if you eat as much honey as white sugar it will be bad for your health. No research was made. He thinks. Many "doctors" say that raw honey is as bad as sugar.Bee products were used by humans since ancient times to ensure the health and building strength and endurance. In ancient Greece, athletes before the Olympics were on a honey diet . Widely known is the fact that only a transition to a honey diet allowed divers to descend to a depth of England's 103 meters in order to raise a sunken World War I passenger ship " Lusitania " with a cargo of gold on board. To raise the power endurance divers have eaten daily by 700 g of honey.Methods of apitherapy (medical use of honey bee products ) is widely recommended for the introduction of a training regimen of athletes of all kinds of sports, but especially in those cases where a high response speed and fine motor coordination - this is boxing , wrestling, tennis , gymnastics, weightlifting. Honey is very useful in sports that require high processing speed - football, basketball , hockey , volleyball , chess and long loads - skiing, ice skating , athletics , swimming, and technical sports . In the USSR, the astronauts also recommended to go to the honey diet.Honey is best consumed over a lifetime , then you yourself secure against many surprises and disease. One day the Emperor Augustus asked the 100th Polly Rumilya the cause of longevity. "Lutus mulso, foris oleo" (" Inside - honey , outside - oil" ) - the elder answered . Honey contains lots of vitamins. What is natural is good.

Do not blindly listen to what scientist “think”. I have even found some articles that scientists “think” that raw apples are bad for health. I eat 3 every day and felling great. Statistics is a very stubborn thing. It shows that people without health problems who lived 100 years + ate meat, fish, different cereals, dairy products, vegetables, fruit and honeyBut in fact there are studies that prove that honey can be BAD: a) when you heat the honey it becomes unhealthy b) if you feed bees with sugar.

I was soooo furious, maybe too much caffiene today? But I really laid into this doctor and I'm not yet feeling Christlike about it and in fact am going to post my angry swearing right here:

Dear Doctor Robert H. Lustig M.D., if you know for a fact that what you said in your posted article about sugar is a lie, I hope you rot in hell. But if in fact you're just stupid, and not actually a doctor or scientist who is capable of doing a little research on your own, then.. I will let you discover the facts on your own. Last time I checked, all of my Fruitarian friends i.e. - people who eat nothing but fructose, tons of it, daily, are the healthiest people, on the planet and longest lived (some over 300 years old, well documented and proven). Also see Michael Arnstein at www.TheFruitarian.com he's a friend of mine who runs a marathon every day on his way to his office, and even won the gold for first place in a nationally famous marathon "AFTER" already running a nationally famous 100 mile race just a few days prior! Doctor, you might use intentionally watered down overly-"shady" science to prove what your boss pays you to.. personally I not only use the facts discovered by the founding men and women who wrote the laws you learned in Med School but I in addition use the facts that I see with my own eyes walking as living proof all around you and me every day, cured of their so-called incurable cancers, AIDS, and every other corporate driven illness, ignorance, poverty, war, pollution you've succeeded in forcing upon mankind and our planet. You might not live long enough to burn, but you'll do so in hell. Keep your hands off our children until you know your own facts. I've watched too many children die in your hands and the so-called Ronald McDonald houses and all other medical institutions that seek children as ravenously as U.S. pedophile politicians do.

Dr. Robert Lustig is a professor of Pediatrics at the UCSF Benioff Children's Hospital and the author of Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity and Disease. The views expressed are solely his own.

@BenArnold1 Your Fruitarian friends who allegedly live to be 300 years old, they are eating fruit, which has fiber. That, as explained in the article, slows the absorption of sugar into the body. Dr. Lustig is not waging a war on fruit. You should really read things more carefully before hoping that someone rots in hell.

@BenArnold1 You should actually read the article and understand it before publicly calling someone a liar and condemning them to an afterlife that doesn't exist. Specifically, read and UNDERSTAND "Myth 5". I don't believe that have understood anything at all.

"I hope you rot in hell"? You, sir, do not understand how to be a pure follower of Christ. You're just another filthy believer who puts all their power into belief WITHOUT taking the time and brain power to understand what they are believing. I'm furious that mentally-challenged and religion-addled person such as yourself has the power to spread your own brand of lies every day without consequences.

I'll lay the truth on you: heavy doses of sugar unmitigated by fiber are actually LESS dangerous than people like you who spread their beliefs (NOT FACT OR TRUTH) like a cancer. I don't hope you burn in a hell-like place. Instead, I hope you spend some of the little time you have been granted, through birth, to get your facts straight and stop misleading others. Unlike you, I'd never look forward to, hope for, or desire someone else's demise. Maybe you can stop being a tiny and petty person before you return to the earth.

and what about too much salt, nitrites, preservatives, fillers, fats etc etc that is put in commercial food to reduce cost and extend shelf life? overindulgence in such foods is bad for longer term outcomes.

The YouTube video is filled with false information. He talks about the high amount of sodium in Coke and Pepsi. High is a subjective term, and really as someone who claims to be educating people has not purpose other than to appeal to people senses instead of facts. Look it up on line and you will see that, depending on the version, most of them have less than 2% of the RDA for a person for sodium.

He then goes on to talk about obese 6 month olds, and said to convince him that diet and exercise alone are not what we think. We it took me a couple minutes to find solid research that shows there are a number of causes of this including simply over breast feeding.

It is too bad a person like this with what is probably some good information buy it is yet another case of a person hyping up one train of thought. It is the same thing when people say no meat or dairy.

The truth is that a well balanced diet with lots of mix of veggies, fruit, smaller meats and carbs AND exercise that gets you a cardio effect are the best ways to get healthy. I know, I did that, lost 52 lbs, lowered my blood pressure and reversed some vascular effects. But that is not very exciting and not an easy sell as demonizing one thing.

Do not believe the lie about sugar being bad not even white sugar. In moderation it is better than any artificial sweetener. A diabetes diet using real sugar caused more weight loss in people with or without diabetes than a sugar free diet using artificial sweeteners.

I know a number of people who are allergic to fructose but not to sugar. For them, they cannot buy sweetened food because fructose is cheaper and used and used everywhere. I quit buying anything with fructose in it.

I'm not going to address the big conclusions in this article but if you are going to try and write a scientific type of article then you might try to get the basic facts correct e.g. Lactose is the sugar in milk which is a disaccharide (contains 2 sugars monomers) , made up of 1 molecule of glucose connected to one of galactose. Lactose is hydrolyzed to give two free monosaccharides, one each of glucose and galactose.

Wow, so that commercial telling me my body can't tell the difference between corn sugar and cane sugar was just misleading propaganda from the corn sugar industry? Say it ain't so! And to think that a LOT of Americans fell for those commercials. You'll find them at the Walmart pharmacy picking up their insulin.

Re Fructose and Addiciton - what research shows that it is fructose that causes addiction? At the Q and A at the Sugar Symposium, Dr Lustig was called out on this and one research showed that rats liked glucose based carbs over sucrose, and another question the applicability of rat research to humans

youtube.com/watch?v=ypWe6npULUQ and youtube.com/watch?v=cnGhfX2yaU4

Also a recent rat studied suggests that it might be the sweet taste and NOT the fructose (as they used an artifical sweetener) although the article title gets it wrong also!

The scientific literature that I've read suggests that the amount of fructose that is turned into fat in humans varies but I've read between 3% and 50%, never any more - any references for this Dr Lustig or do we have to buy the book? (I've attached some below)

It is also interesting to see how poorly Dr Lustig does when talking to his fellow scientists - he was certainly called out for overstating the evidence and poorly extrapolating rat research at a conference he spoke at earlier in the year - check out the Q and A video in the attached article by David Despain!

Also wondering where the 4tsp in 1990 comes from - the link says that "Dietary data from a nationally representative sample in 1977–1978 estimated that mean consumption of fructose was 37 g/day (8% of total intake)" and " The mean consumption of fructose was estimated to be 54.7g/day (range, 38.4–72.8) and accounted for 10.2% of total caloric intake." for the 2008 study - is it a typo?

This is a great article and information about the biological effects of sugar! I had written a blog post about Mayor Bloomberg proposing to limit sugar intakes in NYC back in June 2012; I believe that if someone had to take an initiative to limit the amount of sugar intakes, we can fairly assume that sugar consumption has indeed increased over the years!